DublyLinkedList

#include <iostream>
#include <cstdlib>

using namespace std;


class Numb {
private:
    int value;
    Numb *next;
    Numb *prev;
public:
    Numb(): value(0), next(NULL), prev(NULL) {}
    Numb(int a): value(a), next(NULL), prev(NULL) {}
    ~Numb() {}

    void read() {
        cout << "Enter value: ";
        cin >> value;
    }
    void show() {
        cout << "Value is : " << value << endl;
    }

    int getValue() { return value; }
    void setNext(Numb *N) { next = N; }
    void setPrev(Numb *P) { prev = P; }
    Numb * getNext() { return next; }
    Numb * getPrev() { return prev; }
};


int main() {
    Numb *Head = new Numb();
    Numb *Tail;
    Numb *Current;
    Numb *Previous = Head;

    int choice;

    while(true) {
        cout << "Enter Choice: " << endl;
        cout << "1. Insert (After Head)" << endl;
        cout << "2. Show All" << endl;
        cout << "3. Search (Search for a specefic integer data)" << endl;
        cout << "4. Delete (Find it and Delete it)" << endl;
        cout << "5. Length (Current length of the list)" << endl;
        cout << "0. Exit" << endl;
        cout << "Choice: ";

        cin >> choice;

        if(choice == 0)
            exit(1);

        else if(choice == 1) {
            while(true) {
                Current = new Numb();
                Current -> read();
                Previous -> setNext(Current);
                Current -> setPrev(Previous);

                char cont;
                cout << "Do you want to continue (y/n)? ";
                cin >> cont;
                if(cont == 'n' || cont == 'N') {
                    Tail = Current;
                    break;
                }
                    Previous = Current;
            }
        }

        else if(choice == 2)
            for(Current = Head; Current; Current = Current -> getNext())
                Current -> show();

        else if(choice == 3) {
            int searchValue;
            cout << "Enter Value to Find: ";
            int i;
            cin >> searchValue;
            for(i = 1, Current = Head; Current; i++, Current = Current -> getNext())
                if(Current -> getValue() == searchValue) {
                    cout << "Found in position: " << i << endl;
                    break;
                }
        }

        else if(choice == 4) {
            int searchValue;
            cout << "Enter Value to Delete: ";
            cin >> searchValue;
            for(Current = Head; Current; Current = Current -> getNext()) {
                if(Current -> getValue() == searchValue) {
                    if(Current == Head) {
                        Head = Current -> getNext();
                        Head -> setPrev(NULL);
                    }
                    else if(Current == Tail) {
                        Tail = Current -> getPrev();
                        Tail -> setNext(NULL);
                    }
                    else {
                        Previous -> setNext(Current -> getNext());
                        (Current -> getNext()) -> setPrev(Previous);
                    }

                    delete Current;
                    cout << "Deletion Confirmed" << endl;
                    break;
                }
                else
                    Previous = Current;
            }
        }

        else if(choice == 5) {
            int len = 0;
            for(Current = Head; Current; Current = Current -> getNext())
                len++;
            cout << "Length of the list is: " << len << endl;
        }

        int bak = 1;
        cout << "Enter 0 to go back: ";
        while(bak)
            cin >> bak;
        cout << endl << endl;
    }

    return 0;
}